This invention relates to improvements in line protectors of the type used for protecting telephone lines and like communication lines from over-voltage and over-current conditions as may be caused by electrical power surges, lightning, and the like.
It is known to have protectors of this type include a surge voltage arrester of the cold cathode gas discharge tube type that serves as the primary arrester and source of protection. Such line protectors may also include a carbon or other type of air gap back-up protector in the event of a failure of the primary surge arrester. Such a failure is frequently a result of leakage of gas from the tube due to a broken seal or similar damage. It will be understood that a gas tube arrester which has failed in this manner will be difficult to detect because the line to which it is connected continues to operate properly. Thus, it is desirable to provide some type of air gap or secondary surge arrester as a "back-up" in the event of failure of the gas tube arrester. Line protector units having both gas tube arresters and back-up air gap arresters are known from U.S. Pat. Nos. to Klayum et al 3,755,715 and Bahr et al 3,651,440. In each of the foregoing devices numerous non-standard parts are used. This is in contrast with the desirability of having as many standard parts as possible, namely those parts which presently form portions of known types of line protectors.